1. Field of Invention
The present invention relates to a method of producing a fluid bearing device configured such that dynamic pressure is generated in a lubricating fluid so that a rotating member is supported relative to a stationary member by the dynamic pressure.
2. Related art
Recently, various fluid bearing devices using dynamic pressure of fluid have been proposed for various devices such as motors, particularly in accordance with high-speed rotation. In this type of fluid bearing device, a bearing surface on a stationary member side and a bearing surface on a rotating member side are disposed opposed to each other. A groove for generating dynamic pressure is formed in at least one side of the opposite bearing surfaces. A predetermined lubricating fluid such as oil filled in between the opposite surfaces of the rotating member and the stationary member, that is, in a bearing clearance, is pressurized by a pumping action of the dynamic pressure generating groove when the rotating member is rotated. As a result, dynamic pressure is generated by activation of the lubricating fluid so that the rotating member is rotatably supported by the dynamic pressure.
The lubricating fluid filled in the clearance is held in the bearing clearance by capillary force of capillary seal portions each having an inclined taper surface. Moreover, the lubricating liquid is prevented from being scattered out of the bearing clearance. If the lubricating fluid is exhausted by vaporization, sufficient bearing performance cannot be obtained and reliability, or the like, is worsened. Therefore, the capillary seal portions hold a predetermined quantity of the lubricating fluid inclusive of the predicted quantity of vaporization.
If the quantity of the lubricating fluid inclusive of the predicted quantity of vaporization is, however, too large, fluid leakage occurs to stain the circumference. This is a fatal defect particularly in a hard disk drive device (HDD), or the like, requiring a high cleanness. In the background art, therefore, a surplus lubricating fluid is absorbed by use of capillary force of cloth, or the like, or sucked by an air vacuum, or the like, to thereby stabilize the quantity of the lubricating fluid and hold the lubricating fluid.
In the aforementioned method, however, it is difficult to adjust the fine quantity of the lubricating fluid to a predetermined value, so that it is difficult to stabilize the quantity of the lubricating fluid surely and hold the lubricating fluid. Moreover, a device, or the like, for removing a surplus lubricating fluid is required, so that increase in cost is brought about.
The present invention has been achieved to solve the problem in the background art and an object thereof is to provide a method of producing a fluid bearing device in which a lubricating fluid can be held while the quantity of the lubricating fluid is stabilized surely.
According to the present invention, there is provided a method of producing a fluid bearing device which comprises: a sleeve having a bearing hole; a shaft inserted in the bearing hole; a lubricating fluid interposed in a clearance between the sleeve and the shaft; and capillary seal portions formed in opening portions of the bearing hole and for holding the lubricating fluid; the shaft and the sleeve being supported by dynamic pressure of the lubricating fluid so as to be rotatable relative to each other; wherein the method comprises the step of scattering a surplus of the lubricating fluid in the clearance by centrifugal force, whereby the lubricating fluid is kept in a constant quantity by the capillary seal portions.
By the aforementioned method, the lubricating fluid in the clearance can be held stably and surely. Hence, the life of the fluid bearing device can be elongated. Moreover, the lubricating fluid can be prevented from leaking out when the fluid bearing device is used. Hence, environmental pollution in and around the fluid bearing device can be avoided.